External storage subsystem having independent access paths for permitting independent access from a host and a storage device to respective cache memories

Abstract

A plurality of independent cache units and nonvolatile memory units are provided in a disk controller located between a host (central processing unit) and a magnetic disk drive. A plurality of channel units for controlling the data transfer to and from the central processing unit and a plurality of control units for controlling the data transfer to and from the magnetic disk drive are independently connected to the cache units and the nonvolatile memory units through data buses and access lines.

What is claimed is: 
     
       1. A storage subsystem comprising: a rotating storage device storing data from a host and sending data to the host in response to a request from the host; and   a memory controller including: a plurality of cache memories for storing the data transferred between the host and the rotating storage device,   a plurality of channel units for controlling data transfer to and from the host,   a plurality of control units for controlling data transfer to and from the rotating storage device, and   a plurality of access paths for permitting independent access to the cache memories from the host and independent access to the cache memories from the rotating storage device, the plurality of access paths including a plurality of data buses;     wherein each of said plurality of channel units having a plurality of access lines, each access line connected to each of said plurality of cache memories,   wherein each of said plurality of control units having a plurality of access lines, each access line connected to each of said plurality of cache memories.   
     
     
       2. The storage subsystem of claim 1: wherein the plurality of cache memories includes at least two non-volatile semiconductor memories and two volatile semiconductor memories for temporarily storing the data transferred between the host and the rotating storage device.   
     
     
       3. The storage subsystem of claim 2, further comprising: a plurality of first control processors each associated with one of said plurality of channel units, and a plurality of second control processors each associated with one of said plurality of control units,   wherein access to said cache memories by said channel units and said control units is under the control of said first control processors and said second control processors respectively.   
     
     
       4. The storage subsystem of claim 1, further comprising: a plurality of first control processors each associated with one of said plurality of channel units, and   a plurality of second control processors each associated with one of said plurality of control units,   wherein access to said cache memories by said channel units and said control units is under the control of said first control processors and said second control processors respectively.   
     
     
       5. A storage subsystem comprising: a rotating storage device for storing data from a host and sending data to the host in response to a request from the host; and   a memory controller including; a plurality of groups of cache memories including at least two semiconductor memories for storing the data transferred between the host and the rotating storage device,   a plurality of channel units for controlling data transfer to and from the host, a plurality of control units for controlling data transfer to and from the rotating storage device, and   a plurality of access paths for permitting independent access to the cache memories from the host and independent access to the cache memories form the rotating storage device, the plurality of access paths including a plurality of data buses,     wherein each of said plurality of channel units having a plurality of access lines, each access line connected to each of said plurality of groups of cache memories,   wherein each of said plurality of control units having a plurality of access lines, each access line connected to each of said plurality of groups of cache memories.   
     
     
       6. The storage subsystem of claim 5, wherein the plurality of groups of cache memories includes at least two non-volatile semiconductor memories and two volatile semiconductor memories for temporarily storing the data transferred between the host and the rotating storage device.   
     
     
       7. The storage subsystem of claim 6, further comprising: a plurality of first control processors, each associated with one of said plurality of channel units, and a plurality of second control processors each associated with one of said plurality of control units,   wherein access to said groups of cache memories by said channel units and said control units is under the control of said first control processors and said second control processors respectively.   
     
     
       8. The storage subsystem of claim 5, further comprising: a plurality of first control processors each associated with one of said plurality of channel units, and a plurality of second control processors each associated with one of said plurality of control units,   wherein access to said groups of cache memories by said channel units and said control units is under the control of said first control processors and said second control processors respectively.   
     
     
       9. A storage subsystem comprising: rotating storage storing data from a host and sending data to the host in response to a request from the host; and   a memory controller including: a plurality of channel units coupled to the host, for controlling data transfer to and from the host,   a plurality of control units coupled to the rotating storage, for controlling data transfer to and from the rotating storage,   a plurality of data buses; and   a cache memory for storing the data transferred between the host and the rotating storage, wherein each of said plurality of channel units having a plurality of access lines, each access line connected to each of said plurality of data buses,   each of said plurality of control units having a plurality of access lines, each access line connected to each of said plurality of data buses, and   said cache memory having a plurality of access lines, each access line connected to each of said plurality of data buses.       
     
     
       10. A storage subsystem comprising: rotating storage storing data from a host and sending data to the host in response to a request from the host; and   a memory controller including: a plurality of channel units coupled to the host, for controlling data transfer to and from the host,   a plurality of control units coupled to the rotating storage, for controlling data transfer to and from the rotating storage, and   a plurality of cache memories for storing the data transferred between the host and the rotating storage, wherein each of said plurality of channel units and control units having a plurality of access lines, each access line coupled to each of said plurality of cache memories.       
     
     
       11. A storage subsystem comprising: rotating storage storing data from a host and sending data to the host in response to a request from the host; and   a memory controller including: a plurality of channel units coupled to the host, for controlling data transfer to and from the host,   a plurality of control units coupled to the rotating storage, for controlling data transfer to and from the rotating storage, and   a plurality of cache memories for storing the data transferred between the host and the rotating storage, wherein each of said plurality of channel units and control units having two access lines,   each of one half of said plurality of cache memories having a plurality of access lines,   each access line connected to each of one of said two access lines,   each of the other half of said plurality of cache memories having a plurality of access lines, each access line connected to each of the other of said two access lines.       
     
     
       12. A storage subsystem comprising: rotating storage storing data from a host and sending data to the host in response to a request from the host; and   a memory controller including: a plurality of channel units coupled to the host, for controlling data transfer to and from the host,   a plurality of control units coupled to the rotating storage, for controlling data transfer to and from the rotating storage, and   a plurality of cache memories for storing the data transferred between the host and the rotating storage, wherein each of said plurality of cache memories having two access lines,   each of said plurality of channel units having a plurality of access lines, each access line connected to each of one of said two access lines of said cache memories,   each of said plurality of control units having a plurality of access lines, each access line connected to each of the other of said two access lines of said cache memories.       
     
     
       13. A storage subsystem comprising: rotating storage storing data from a host and sending data to the host in response to a request from the host; and   a memory controller including: a plurality of channel units coupled to the host, for controlling data transfer to and from the host,   a plurality of control units coupled to the rotating storage, for controlling data transfer to and from the rotating storage,   a plurality of data buses; and   a plurality of cache memories for storing the data transferred between the host and the rotating storage, wherein each of said plurality of channel units having a plurality of access lines, each access line connected to each of said plurality of data buses,   each of said plurality of control units having a plurality of access lines, each access line connected to each of said plurality of data buses, and   each of said plurality of cache memories having a plurality of access lines, each access line connected to each of said plurality of data buses.       
     
     
       14. A storage subsystem comprising: rotating storage storing data from a host and sending data to the host in response to a request from the host; and   a memory controller including: a plurality of channel units coupled to the host, for controlling data transfer to and from the host,   a plurality of control units coupled to the rotating storage, for controlling data transfer to and from the rotating storage,   a plurality of data buses; and   a plurality of cache memories for permitting independent access to the data transferred between the host and the rotating storage, wherein each of said plurality of cache memories having a plurality of independent access lines, which permit for each access line independently access to said plurality of channel units and said plurality of control units.